The present disclosure relates generally to the field of medicine and more particularly to the field of anesthesiology and the assessment of the effects of anesthetic drugs using an electroencephalogram (EEG).
Quantitative assessment of EEG data is used in basic and clinical research. The collection of simultaneous, multiple-channel EEG recordings allows one to be quickly overwhelmed by quantities of data from which rules and relationships can be difficult to sift. Consequently, much of the effort to evaluate this data has been directed towards determining global parameters from the EEG that can correlate with observations seen clinically for a number of normal and pathological conditions. However, the complexity of analysis of EEG data limits the use of EEG to monitor anesthesia.
There are 40 million surgical interventions performed annually in the U.S. under general anesthesia. The number of surgical and anesthesia-based interventions, both therapeutic and diagnostic, is expected to increase as the population ages. There is more than double that number worldwide. (See, EEG Processor Monitor Market Opportunities, Strategies, and Forecasts, 2003 to 2008. 2003, WinterGreen Research Inc.) Recent evidence from Sandin et al. gives credence to the need to monitor the complete anesthetic state. (See, Sandin, R., G. Enlund, P. Samuelsson, and C. Lennmarken, Awareness during anesthesia: a prospective case study. The Lancet, 2000. 355: p. 707-711.) In a prospective study of surgical patients, Sandin et al. showed an incidence of awareness during anesthesia of 0.1-0.2%. While most of the awareness incidents were benign, this still underscores the challenge faced by clinicians in administering drugs to depress the CNS.
There is a need for a system and method for determining the analgesic component to an anesthetic state of a patient. There is a need for a method to distinguish the amount of an analgesic and the amount of a sedative that contribute to an anesthetic state of a patient during surgical procedures. There is yet another need for a means to provide the output of the information collected from the method above to an attending anesthesiologist during a surgical procedure. Further still, there is a need for a pseudo-real time, direct computational method that does not rely on a database of empirical data which is drug-specific.